Introducing a new cache design into vector computers

Registers within a processor, cache within, on, or outside the processor, and virtual memory on the disk drive builds memory hierarchy in modern computer systems. The principle of locality of reference makes this memory hierarchy work efficiently. In recent years, cache organizations and designs have witnessed several advances that have not only improved their performance such as hit rates, speed, latency, energy consumption, etc. but various new designs and organizations for chip multi-processors such as multilevel caches, Non-Uniform Cache Access (NUCA), hybrid caches, etc. have also emerged. This paper presents a study of current competing processors in terms of various factors determining performance and throughput of cache organization and design. To evaluate their performance and viability, it reviews recent cache trends that include hybrid cache memory, non-uniform cache architecture, energy efficient replacement algorithms, cache memory programming, software defined caches and emerging techniques for making cache reliable against soft errors. It discusses the pros and cons of emerging cache architectures and designs.

Simplified analytical models are developed for evaluating the thermal performance of closed-wet cooling towers (CWCTs) for use with chilled ceilings in cooling of buildings. Two methods of simplification are used with regard to the temperature of spray water inside the tower. The results obtained from these models for a prototype cooling tower are very close to experimental measurements. The thermal performance of the cooling tower is evaluated under nominal conditions. The results show that the maximum difference in the calculated cooling water heat or air sensible heat between the two simplified methods and a general computational model is less than 3%. The analytical model distribution of the sensible heat along the tower is then incorporated with computational fluid dynamics (CFD) to assess the thermal performance of the tower. It is found that CFD results agree well with the analytical results when the air flow is simulated with air supply from the bottom of the tower, which represents a uniform air flow. CFD shows the importance of the uniform distribution of air and spray water to achieve optimum design. Copyright © 2002 John Wiley & Sons, Ltd.

In chip multiprocessors (CMPs), data access latency depends on the memory hierarchy organization, the on-chip interconnect (NoC), and the running workload. Reducing data access latency is vital to achieving performance improvements and scalability of threaded applications. Multithreaded applications generally exhibit sharing of data among the program threads, which generates coherence and data traffic on the NoC.Many NoC designs exploit communication locality to reduce communication latency by configuring special fast paths on which communication is faster than the rest of the NoC. Communication patterns are directly affected by the cache organization. However, many cache organizations are designed in isolation of the underlying NoC or assume a simple NoC design, thus possibly missing optimization opportunities. In this work, we present a NoC-aware cache design that creates a symbiotic relationship between the NoC and cache to reduce data access latency, improve utilization of cache capacity, and improve overall system performance. Specifically, considering a NoC designed to exploit communication locality, we design a Unique Private caching scheme that promotes locality in communication patterns. In turn, the NoC exploits this locality to allow fast access to remote data, thus reducing the need for data replication and allowing better utilization of cache capacity. The Unique Private cache stores the data mostly used by a processor core in its locally accessible cache bank, while leveraging dedicated high speed circuits in the interconnect to provide remote cores with fast access to shared data. Simulations of a suite of scientific and commercial workloads show that our proposed design achieves a speedup of 14% and 16% on a 16-core and a 64-core CMP, respectively, over the state-of-the-art NoC-Cache co-designed system which also exploits communication locality in multithreaded applications.

Most of today's microprocessors have an on-chip cache to reduce average memory access latency. These on-chip caches generally have low associativity and small sizes. Cache line conflicts are the main source of cache misses which are essential to overall system performance. This paper introduces an innovative, conflict-free cache design, called one's complement cache. By means of parallel computation of cache addresses and memory addresses of data, the new design does not increase critical hit time of cache accesses. Cache misses caused by line interferences are minimized by means of evenly distributing data items referenced by program loops across all sets in a cache. Evenly distribution of data in the cache is achieved by making the number of sets in the cache a prime or an odd number thereby the chance of related data being mapped to a same set is small. Trace-driven simulations are used to evaluate the performance of the new design. Performance results on a set of programs from SPEC92 benchmarks show that the new design improves cache performance over the conventional set-associative cache by about 100% with negligibly additional hardware cost.

The Chinese Knot inspired anisotropic TC4 lattice Structures: Ultra-high specific strength in engineering materials

Cache memory has grown to be an essential component of CPU architecture due to the growing gap between processing power and main memory access latency. The cache design that processors use has numerous levels, with the smallest, fastest private caches (Level 1) supported to the largest, slowest caches (Level 2). Snoop Control Units (SCUs) have been added to multi-core processors to ensure the coherency of private cache data. The literature that is currently available discusses application-specific cache alignment methods. When inter-core communication begins to function at the OS level, Symmetric Multi-Processing (SMP)/Asymmetric Multi-Processing (AMP) Real Time Operating Systems (RTOS) will add a significant amount of overhead to system activities. This study is the first to propose an unique signalling technique between the cores based on cache aware information lookups. It is implemented as "SCHEDULE-ASSIST" and "ENTITY-ASSIST" in the Little Kernel scheduler, an SMP RTOS scheduler. We demonstrate an up to 13% improvement in RTOS processing Key Performance Indices (KPI) for RTOS’ Application Programming Interfaces (APIs) compared to schemes that are unaware of the cache design through analytical modelling and implementation using a Xilinx Evaluation Kit.

A generic computational model of mood regulation and its use to model therapeutical interventions

The collapse strength of flexible pipes is a well known property and predicted by means of numerical or analytical modelling. However, recent oil field discoveries in the Brazilian pre-salt area, in water depths up to 2500m, are pushing the industry to evaluate the effects of flexible pipe curvature on its collapse resistance when the pipe is subjected to extreme levels of hydrostatic pressure such as that expected in the Brazilian pre-salt area. As part of Wellstream's R&D programme, a numerical model was specifically developed to predict flexible pipe collapse resistance when subjected to curvature to assess and quantify the effects of curvature on the flexible pipe collapse resistance. This paper summarizes the numerical modelling process and experimental calibration performed using five different pipe structures specifically designed for the pre-salt cluster. A total of 45 calibration tests were performed using samples taken from the same production run in order to eliminate variance in production machine setup and raw material batches. Regular production equipment, setups and quality control procedures were used to manufacture the test samples so that the collapse resistance of the pipes could be evaluated against conditions identical to commercial manufacturing. Of the five different pipe structures evaluated in this test programme, one of the pipe structures supplied for the TUPI EWT project development is already installed and operating at a water depth of 2140m. The test programme allowed the experimental assessment of the curvature effects on flexible pipe collapse behaviour, demonstrated the suitability of flexible pipe structures and model to predict the effects of curvature on collapse resistance. Introduction The industry is focusing on the latest offshore discoveries in the Brazilian pre-salt cluster due to the huge volumes of oil and gas identified in this new exploratory frontier. However, the technological challenges associated with this development are significant and mainly affect subsea equipment suppliers. The ultra deepwater, which can reach up to 2500m, and the presence of contaminants such as CO2 and H2S in the conveyed fluids are major challenges to be addressed. The presence of H2S in the conveyed fluids may make the selection of lower strength metallic materials compulsory to avoid HIC and SSC failures; such failures would be a problem when massive service pressures and loads are expected in service. This scenario requires an innovative design approach to consolidate new technologies and create a pipe structure that can withstand the service requirements. In 2008, Wellstream established a global R&D programme focused on the development of a new generation of flexible pipes specifically designed for the Brazilian pre-salt cluster. This programme has a diverse scope of work addressing aspects such as metallic and polymeric material development, product evolution, product innovation, model calibration, and alternative design solutions. This paper focuses on Wellstream's approach in improving the collapse resistance of flexible pipes designed for the Brazilian pre-salt area, summarizing the FEA model development and calibration, and test programme. Although the industry has established both analytical and numerical modelling techniques to predict flexible pipe collapse resistance, some concerns regarding the suitability of flexible pipes for service in water depths of up to 2500m have been raised; this is mainly due to the bending radius expected for the flexible pipes in the touchdown zone (TDZ) during installation and operation.

Introduction. Currently, almost all spheres of society life activities are developing in terms of progressive digitalization, therefore it is required to promptly transform existing approaches to organizing the student learning process. The purpose of research: to determine digital competencies relevant to the field of professional activity of graduates of artistic and creative areas of training and to actualize the content of the educational process in accordance with the results obtained. Materials and methods. The study was conducted during 2021 – 2023 on the basis of the Department of Design, Art Education and Technology of Yelets State University named after I.A. Bunin. The target group included 157 respondents with experience in conducting creative activities using modern digital technologies. Empirical test methods for data collection were implemented in two ways: during direct communication and remotely using Yandex Forms. Quantitative statistical analysis was carried out using LibreOffice Calc. Results. 6 enlarged groups of digital competencies of graduates of artistic and creative areas of training, currently in demand by society and the labor market, have been identified. Based on the opinions of the respondents, they were ranked according to the degree of importance: have the skills and abilities to work with raster (16.6%) and vector (12.1%) computer graphics, design and edit pages or sites on the Internet (13.3%) , develop multimedia content (5.7%), create and edit 3D models (23.6%), use specialized programs according to the training profile (28.7%). Conclusions. The empirically obtained results were integrated into the curriculum for undergraduate training in the direction 54.03.01 Design, specialty (profile) “Design and Contemporary Digital Art”, in terms of the proportional distribution of study time between disciplines and modules focused on the development of digital competencies. The optimal sequence of developing skills in mastering specialized digital tools has been identified, which is the key to the effective outcome of the educational process. Promising vectors for the development of artistic and creative education of students have been identified, which include: design of mobile applications, creation of elements of augmented and virtual reality, development of conceptual digital games.

CuGBasis is a free and open-source CUDA®/Python library for efficient computation of scalar, vector, and matrix quantities crucial for the post-processing of electronic structure calculations. CuGBasis integrates high-performance Graphical Processing Unit (GPU) computing with the ease and flexibility of Python programming, making it compatible with a vast ecosystem of libraries. We showcase its utility as a Python library and demonstrate its seamless interoperability with existing Python software to gain chemical insight from quantum chemistry calculations. Leveraging GPU-accelerated code, cuGBasis exhibits remarkable performance, making it highly applicable to larger systems or large databases. Our benchmarks reveal a 100-fold performance gain compared to alternative software packages, including serial/multi-threaded Central Processing Unit and GPU implementations. This paper outlines various features and computational strategies that lead to cuGBasis's enhanced performance, guiding developers of GPU-accelerated code.

Due to a number of attractive advantages, cooperative communications have been widely regarded as one of the promising techniques to improve throughput and coverage performance in wireless communications. The relay node (RN) plays a key role in cooperative communications, and RN selection may substantially affect the performance gain in a network with cooperative media access control (MAC). In this paper, we address the issue of RN selection while taking into account MAC overhead, which is incurred by not only handshake signaling but frame retransmissions due to transmission failure as well. We design a cooperative MAC mechanism with our optimal RN selection algorithm, which is called optimal relay selection MAC, and use a theoretical model to analyze the cooperation performance gains. We conduct simulation experiments based on Network Simulator to evaluate our proposed cooperative MAC. Numerical results validate the effectiveness of our analytical model and show that our designed MAC significantly outperforms existing cooperative MAC mechanisms that do not take into account retransmission MAC overhead.

Learning outcome is an important measure for overall teaching quality and should be addressed by comprehensive evaluation tools. The authors evaluated the validity of a novel evaluation tool based on student self-assessments, which may help identify specific strengths and weaknesses of a particular course. In 2011, the authors asked 145 fourth-year students at Göttingen Medical School to self-assess their knowledge on 33 specific learning objectives in a pretest and posttest as part of a cardiorespiratory module. The authors compared performance gain calculated from self-assessments with performance gain derived from formative examinations that were closely matched to these 33 learning objectives. Eighty-three students (57.2%) completed the assessment. There was good agreement between performance gain derived from subjective data and performance gain derived from objective examinations (Pearson r=0.78; P<.0001) on the group level. The association between the two measures was much weaker when data were analyzed on the individual level. Further analysis determined a quality cutoff for performance gain derived from aggregated student self-assessments. When using this cutoff, the evaluation tool was highly sensitive in identifying specific learning objectives with favorable or suboptimal objective performance gains. The tool is easy to implement, takes initial performance levels into account, and does not require extensive pre-post testing. By providing valid estimates of actual performance gain obtained during a teaching module, it may assist medical teachers in identifying strengths and weaknesses of a particular course on the level of specific learning objectives.

Fiber-reinforced polymer (FRP) composites offer several advantages in relation to traditional materials, such as high specific strength, good corrosion resistance, low thermal conductivity and rapid component installation. Despite the great potential of these materials, two major disadvantages limit their acceptance in civil engineering applications: their lack of inherent ductility and the fact that their fibrous and anisotropic character makes the joining of structural components difficult. The purposes of this research are to develop ductile structures using brittle all-FRP materials and to provide a corresponding design method assuring robustness and structural safety. The proposed concept for all-FRP structures incorporates system ductility through the use of ductile, adhesively-bonded joints and redundant (statically indeterminate) structural systems. The concept envisages adhesives with an initially elastic behavior sufficiently stiff to meet short- and long-term serviceability requirements. When serviceability and ultimate loads are exceeded, however, adhesive behavior should change and become plastic, or at least highly non-linear inelastic, with much lower stiffness. The ductile connections effect a favorable redistribution of internal and external forces in the redundant system in the same way as plastic hinges in statically indeterminate systems with ductile materials. In case of joint failure, the redundant system allows the creation of alternative load paths and redistribution of section forces preventing structural collapse. Numerical and experimental investigations of adhesively-bonded double-lap joints demonstrate that using an appropriate bilinear adhesive is more advantageous than using a traditional structural and stiff epoxy adhesive. These investigations show that ductile adhesives generate a linear axial strain distribution and consequently a constant shear stress distribution along the overlap. Numerical and analytical modelings are validated with experimental results. The numerical modeling allows evaluation of the effect of ductile adhesive behavior on joint behavior and establishment of recommendations for the selection of adhesive mechanical properties, according to serviceability and failure limit state requirements. Based on numerical modeling results, joints can also be classified according to stiffness (stiff or flexible). An analytical model, based on numerical and experimental results, is developed for predicting joint stiffness when using ductile adhesives, assuming that the adhesive deforms only and uniformly in shear and that adherends deform only in tension. The design method is developed in accordance with the new structural concept and Eurocode design philosophy. It is based on both numerical and analytical model results for adhesively-bonded double-lap joints. A case study illustrating the adhesively-bonded joint design and appropriate adhesive selection is carried out on continuous beams with adhesively-bonded joints at mid-support. Corresponding bending experiments on beams with ductile, adhesively-bonded connections demonstrate the new structural concept's feasibility and validate the proposed design method. An energy factor defined as the ultimate strength to serviceability limit state energy ratio is proposed to quantify and compare the robustness and safety of structures built from both ductile and brittle materials.

We study the blocking probability and performance of single‐fiber and multifiber optical networks with wavelength division multiplexing (WDM). We extend the well‐known analytical blocking probability model by Barry and Humblet to the general model, which is proposed for both single‐fiber and multifiber network paths with any kind of wavelength conversion (no, limited, or full wavelength conversion) and for uniform and nonuniform link loads. We investigate the effect of the link load, wavelength conversion degree, and the number of wavelengths, fibers, and hops on blocking probability. We also extend the definition of the gain of wavelength conversion by Barry and Humblet to the gain of performance, which is fully general. Thanks to this definition and implementation of our model, we compare different WDM node architectures and present interesting results.

To enhance the overall energy efficiency of the individual parts used in automobile and aerospace industries, study of the specific strength of the components becomes crucial. As a result, in the last couple of decades, large efforts have been made to develop porous architecture with light weight and high specific strength. Herein, an easily scalable and controlled processing of a stochastic bicontinuous atomic scale structure inspired complex porous architecture using 3D printing is demonstrated. The complex topology of the architecture provides enhanced mechanical properties (specific strength, modulus, specific energy absorption etc.). These properties can be easily tuned with the help of changing density and surface area. Based on experimental observations, an analytical model is proposed to correlate these properties with density. These individual architectures can be stacked on top of each other with different combinations to build hierarchical structures, which allows engineering of the directional dependency of the mechanical response.